Association between advanced generations and genealogy in inbred lines of snap bean by the Ward-Modified Location Model

Genetics of resistance to ascochyta blight was studied using different generations of fifteen crosses of chickpea (Cicer arietinum L.). Six parents comprising two susceptible varieties GL 769, C 214 and four resistant lines GG 1267, GL 90168, GL 96010 and GL 98010 were used to develop one S × S, eight S × R and six R × R crosses and some of the back crosses and F₃ generations were developed. Field screening technique was used to evaluate the different generations for disease reaction using mixture of ten prevalent isolates (ab₁–ab₁₀) of ascochyta blight (Ascochyta rabiei). Inheritance study showed digenic recessive control of resistance in the cross GL 769 × C 214, whereas monogenic recessive control of resistance was found in the crosses GL 769 × GL 98010 and C 214 × GL 98010. Digenic dominant and recessive control of resistance was found in the crosses GL 769 × GG 1267 and C 214 × GG 1267 while the crosses GL 769 × GL 90168 and C 214 × GL 96010 showed the monogenic dominant control of resistance. Trigenic dominant and recessive control of resistance was observed in the crosses GL 769 × GL 96010 and C 214 × GL 90168. Allelic relationship studies showed that three resistant parents viz., GG 1267, GL 96010 and GL 90168 possessed allelic single dominant gene for resistance. Besides, GG 1267 possessed two minor recessive genes for resistance, one of them was allelic to the minor recessive gene possessed by GL 90168 and other with GL 96010. The resistant parents GL 90168 and GL 96010 possessed non-allelic minor gene for resistance. The resistant parent GL 98010 possessed two minor recessive genes for resistance which were allelic to respective single recessive gene for resistance possessed by the susceptible parents GL 769 and C 214. The susceptible parents GL 769 and C 214 also possessed single independent inhibitory dominant susceptibility gene. The inhibitory gene was epistatic to the corresponding recessive gene for resistance.